Fortresses are both map types and a game mode in eternal crusade. They feature an attacker with access to many vehicles such as transports, tanks, and ordnance, as well as defenders that are usually limited to tanks. The appeal of fortress matches are their long drawn out conflicts measuring slow gains against stalwart defences and the need for attackers to hammer the defenders' positions while the defenders fight to keep the attackers, whose lives are without number, from succeeding in their assault.

There are two points in Fortress maps. The first ("A") point usually holds between 50-70 spawns or "lives". Meanwhile the two gates hold circa 50 each. When these gates are destroyed the lives on them that have not been spent are transferred to B. Note that B may only be captured once A has been captured.

Most fortresses have a direct means of entry (destroying the gates) and several indirect means (smaller paths only large enough for infantry to move through) Using a combination of these paths is key to victory as an attacker.

The second point is usually within a large cathedral and it is usually the most difficult part of an attacker's assault as it features several railings and chokepoints the defenders can use to lock attackers out. Jump packs are at their highest use here, especially those equipped with grenades as they can disrupt the enemy. Be warned though, it is usually a long walk from A to B.